Bone Marrow Transplantation

What is bone marrow transplantation and how is it performed?

It is the procedure of transplanting the bone marrow intravascularly, which is collected from a healthy person to the patient with the blood / bone marrow disease, cancer or congenital disease, to provide treatment. For the bone marrow to match, the marrow and blood cells of the patient should be removed. Thus, the patients’ blood cells and bone marrows are destroyed by administering very high doses of cancer medications (chemotherapy), even if the patients do not have cancer. This procedure generally takes 7 to 10 days. At the end of this stage, the bone marrow of the patient becomes non-operative and reconstruction of blood cells stops. It takes approximately 15-20 days for the new marrow to establish itself. Until the bone marrow establishes itself, an infection/fever, mouth sores, diarrhea, bleeding and hair loss can occur due to weakened immune system against bacteria, as blood cells are not fully developed. Additionally, other side effects (related to internal organs such as liver, kidney, heart and others) may occur due to high doses of medications. In order to prevent these side effects, the patients will receive blood transfusions, blood products (platelets, plasmas) and preventive medications. The patients are observed in sterile and hepa filtered rooms if possible; special diets are prepared carefully for proper nutrition. By offering continuous oral care, we attempt to prevent mouth sores. However, the oral nutrition becomes difficult, as a result of mouth sores, loss of appetite and decreased sense of taste which occur in most of the patients. During this period, most patients can receive IV supplements. Once the marrow establishes itself in 15-20 days, fever reduces and mouth sores heal. The patients can be discharged within approximately 1 month after the bone marrow transplant. However, the serious side effects can be observed in particular patients; 10-30% of patients can be lost within the first 3 months, due to these serious side effects. The discharged patients will continue to take particular oral medications and receive additional IV medication once a month. Generally, all medications are discontinued within 6 months. They may return to school in 6-8 months. Due to the heavy medications administered to the bone marrow transplant patients, the vaccines that have been previously administered may lose their effectiveness; therefore it is required to resume vaccines within 9-12 months.

What are the long-term side effects of bone marrow transplantation?

Due to the high doses of chemotherapy and the radiotherapy in certain cases, a delay in development/short stature, disorders that are related to the thyroid gland, osteoporosis, delays/problems in puberty development, cataract formation may occur. The treatments and preventions of these diseases may be possible with frequent checkups. Infertility may be observed, when the patients reach adulthood. The patients who receive the transplant are at greater risk of developing a different type of cancer (for instance, skin) compared to healthy individuals, however this risk is not high.

What is stem cell? Can blood or umbilical cord blood be used as stem cell source, instead of bone marrow?
The stem cell is the main cell that is found in the bone marrow and it helps the marrow to establish itself and produce healthy bone marrow and blood cells. In fact, the term "stem cell transplant" is generally used instead of "bone marrow transplant". The "Stem cell transplant" is a general term used that also includes bone marrow, blood stem cell or umbilical cord blood transplants. Any of these three can be used. Although the bone marrow transplant is the most common one for children, the blood stem cell transplants and umbilical cord blood transplants have been spreading.
Under normal conditions, there are very few stem cells in the blood. After applying an injection (vaccine) called growth factor to the donor for 4-5 days, the stem cells pass to the blood from the bone marrow and the stem cell collection with an apheresis instrument, can be used instead of the bone marrow transplant. The apheresis device is an instrument that is used to obtain certain blood products at the blood bank. The blood vessels in both arms of the donor are entered in and connected to the device, and the procedure is completed in few hours. The donor is not required to be hospitalized. It has almost no risk for the donor.

The umbilical cord blood is normally a product that gets discarded after birth. The cord blood has stem cells, same as the kind that can be found in the bone marrow. Therefore, the cord blood can be collected during birth and can be frozen to be used as needed instead of a marrow transplant. If a patient has a disease that requires a bone marrow transplant and if the mother is pregnant, it will be appropriate to collect and preserve the cord blood from the sibling at birth. The collected cord blood can be used instead of a bone marrow transplant even if it only matches partially with the patient’s tissue type.

For which diseases is the bone marrow transplant applied to children?

Diseases related to blood or bone marrow:
Severe aplastic anemia
Fanconi aplastic anemia
Blood cancer (leukemia): AML, recurrent or high risky ALL, KML, MDS
Mediterranean anemia (thalassemia) (early stage)
Genetic immune deficiencies (deficiency of immune system)

Genetic metabolic diseases
Other cancers (certain childhood brain tumors or other childhood tumors)

Who is the most appropriate donor for a bone marrow transplant?

The tissue types of the donor and patient must match for a bone marrow transplant to be administered. The most appropriate donor is the sibling, with matching tissue type. The patient’s father or mother’s tissue type only matches partially. A full match is seen rarely. If there is not a tissue-matching sibling or another family member, testing all relatives is generally useless. The possibility of finding a appropriate donor among other relatives is very low. When a full match family member cannot be found, it is so risky to transplant a bone marrow (or stem cells) from a non-matching person. The success rate is really low. However, it can be successful in patients with congenital immune deficiency.

What is tissue type compatibility? How is it tested?

The designation of tissue types is performed in order to find the most compatible donor for the patient. The blood is drawn for this reason. The tissue types are the particular signs on leukocytes (white blood cells) in blood. These are called HLA-tissue types. The tissue types are different from the blood groups. The blood groups are the particular signs of erythrocytes (red blood cells). The blood group compatibility is not required for the tissue type compatibility. If the patient’s and the donor’s tissue types match, the transplant can be performed even if the blood groups are different. However, it is preferable for the blood groups to be the same. The blood is taken from the patient, siblings and mother and father, if alive, for tissue type designation. The collection of bone marrow is not required for the tissue type definition.

How is bone marrow extracted from the donor? Is it harmful for the donor?

If there is a matching sibling in the family, she/he is tested whether she/he is appropriate for the transplant. The blood tests / certain simple laboratory tests are performed. The collection of the bone marrow from the donor is practiced with anesthesia. The marrow is collected using syringe needles from the hipbone of the donor. The collected amount varies according to the weight of the patient. The bone marrow collection procedure causes practically no harm to the donor. Only a few side effects of this procedure have been reported. The collection is performed under surgery conditions. A slight anemia can be seen in the donor. The donor returns to normal with the help of iron supplement pills in a matter of couple weeks. A blood draw is not required. The donor can return to work or school within 3-5 days.

What should be done in the event of that a suitable donor cannot be found in the family?
If there is not a suitable donor in the family, the bone marrow or cord blood banks can be searched. However, finding a full-match (6/6 HLA matched) donor is not always possible, considering that there is not a real bank, particularly in Turkey. There are a few centers which are still being established. It is difficult to find a suitable donor for a Turkish patient from the banks abroad. When it is found, the transportation of the marrow or cord blood to Turkey can be possible under certain circumstances. However, there are greater risks in transplants from foreigners, and the success rate is lower. A number of centers have been dealing with creating a bank in Turkey due to difficulties and risks of providing bone marrow or cord blood from abroad for patients in Turkey. However, a comprehensive and real bank has not been established yet. The tissue types of 7-8 million volunteers have been identified in various banks across the world. If the tissue of a donor matches with the patient’s, the date is determined for the collection of bone marrow by contacting the donor. It is easier to obtain the cord blood, when found. Because the cord blood is preserved in the bank as collected, frozen and tested. It is easy to reach the product when needed. However, an adequate amount may not be obtained as the collected cord blood amount may be very little (particularly in overweight patients).

What is autologous bone marrow (or stem cell) transplantation? For which diseases it is practiced? How many years can the frozen stem cells be preserved?
The autologous marrow transplant may be preferred first for childhood tumors or if a suitable donor is not found. The autologous transplant is the procedure of retrieving the patient's own bone marrow, and administering it back to the patient after being exposed to high doses of chemotherapy. For tumors and certain blood cancers, after the patient is administered chemotherapy and a large part of cancer cells are destroyed (after the marrow is cleansed partially), the bone marrow is collected and stored in liquid nitrogen tanks at -180°C. The stem cells maintain viability more than 10 years, when stored under these conditions. Then the patient is applied high doses of chemotherapy / radiotherapy. Almost all cancer cells are attempted to be destroyed. The bone marrow of the patient becomes completely non-operative. The blood cells cannot be produced. The blood formation is obtained by applying defrosted marrow. In autologous transplant, the risk of recurrence of the disease is higher, since the patient's own marrow is re-transfused. However, the side effects and treatment-related death rate is lower.